U.S. Pat. No. 2,324,291 discloses a radial piston machine including a star-shaped driving means on which radial pistons abut which are arranged like a star in the housing. The driving means is slipped onto stamp-like projections of the radial pistons to guide the radial pistons. This provides a positive clamping engagement of the piston stamps so that, on rotation of an eccentric gear arranged in the driving means, the movement of the driving means follows the movement of the eccentric. Due to the disclosed arrangement of the radial pistons on the driving means and the arrangement of the driving means with respect to the eccentric, a relative movement occurs between the contact surfaces of the piston stamps and the driving means which, due to friction on the contact surfaces and a tilting moment effect of the radial pistons in the housing, reduces the pump output and forces the driving means to clamp the pump stamps, which has adverse effects on the rigidity of the driving means.
British patent specification No. 763 095 discloses a driving means for a radial piston pump which, for the assembly, has a bipartite design in a radial direction and embraces the eccentric drive. The relative movement between the driver and the eccentric gear is ensured by a radial clearance which is configured as a sickle-shaped slot. The driver, which is hence composed of half shells, in terms of its material strength, must be dimensioned so that the tensile stress caused by screws can be taken up by the driver both mechanically and geometrically. Accordingly, the driver has a large and heavy construction. In addition, it can only be mounted in a radial direction because it is screwed with the piston.